I obsess (I will be positive and say 'intently focus') about plants and music.
I would easily spend all my time on these two things. I'll just talk about plants right now, otherwise I would type all night.
I research plant taxonomy in my spare time. I could recite you encyclopedic lists of information on just about any plant you could name. My garden is not based on "oh, that's pretty." I've arranged plants in the yard by botanical families, shared cultural traits, places of origin, etc... More like a showy and deliberate botanical garden. Except, I'm the only one that ever sees it.
I bore the hell out of people I know as I inform them about the virtues of a particular rose rootstock, or the wonders of curious tree-sized sunflowers from Bolivia, or the distinctions between the different species of Eucalyptus, or when the camellias come into bloom. It really is almost like "seeing only trees at the expense of the forest". Other people look at the whole of my garden and find it chaotic and strange. It makes perfect sense to me.
I've always communicated with plants. I intuitively pick up on signals from them, and I can reliably guess at what they need if they are not thriving. I spend time just "being" around a particular tree. I've always preferred their company to that of people.
obsessed? yeah, I guess so

I'm not even interestd in plants other than aestetics, but you've caught my interest. I enjoy hearing other people ramble just as much as I like to ramble.